Paper sizing agents containing cationic dispersants

ABSTRACT

A cationic dispersant composed of a copolymer made of the monomers N,N-dimethylamino acrylate and/or methacrylate, the acrylic acid ester and or methacrylic acid ester of a C 10  to C 22  fatty alcohol, methyl acrylate and/or methyl methacrylate, acrylic and/or methacrylic acid and optionally n-butyl acrylate and/or methacrylate and isobutyl acrylate and/or methacrylate. It is equally suitable for the production of stable sizing agent dispersions intended for internal or surface sizing.

This is a division of application Ser. No. 548,417 filed Jul. 5, 1990,now U.S. Pat. No. 5,116,924.

CROSS REFERENCE TO RELATED APPLICATION

The present disclosure relates to the subject matter disclosed inapplication No. 89112252.5 filed in the European Patent Office on Jul.5th, 1989, the entire specification of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the production of the novel dispersantsand the sizing agent dispersions produced therefrom which areadvantageously employed for sizing paper. The invention further relatesto cationic dispersants for the dispersion of sizing agents, for examplerosins and/or derivatives thereof, and reactive sizing agents, forexample alkyl ketene dimers, as well as cationic sizing agentdispersions containing these dispersants and possibly also aluminumsulfate.

2. Technology Review

Aqueous resin dispersions for sizing paper are known. Resin dispersionsbased on natural resins, e.g. rosin resins, possibly containing polymerssuch as starches that have been crosslinked, possibly under alkaliconditions, with methyl cellulose, casein or other proteins aredisclosed in many patents. For example, resin dispersions made accordingto the Bewoid process, are mentioned in German Pat. No. 1,131,348. U.S.Pat. No. 3,955,654 describes resin dispersions produced by high pressurehomogenization.

Also known are cationic dispersions of paper sizing agents in water inwhich cationic starches or cationic, synthetically produced polymers areusually employed as the cationically active substances. The presence ofthe cationically active substances considerably accelerates the sizingprocess.

U.S. Pat. No. 3,966,654 discloses aqueous dispersions of paper sizingagents in water which are composed of 5 to 50 weight percent of afortified resin, 0.5 to 10 weight percent of a water-soluble cationicdispersant and water. The fortified resins employed here are primarilywood and tall oil rosins which have been reacted with compositionscontaining the group >C═C--C═O. The cationic dispersant may be polyamineepichlorohydrin resins, alkylene polyamine epichlorohydrin resins orpolydiallylamine epichlorohydrin resins. The disadvantages of thesedispersions are that their shelf life stability still leaves somethingto be desired.

Aqueous dispersions of finely dispersed and fortified resin sizingagents are the subject matter of U.S. Pat. No. 4,374,673 which isrelated to European Patent 0,056,876. Instead of the dispersantsdisclosed in U.S. Pat. No. 3,966,654, this process employs cationicstarches as the water-soluble dispersants. Moreover, they also containan anionic surfactant. The remainder of the dispersion is water. Thedispersions employed for sizing paper can be produced either byhomogenization of a solution or melt of the fortified resin in ahomogenizer under pressure or according to the so-called inversionprocess. In the firstmentioned process, the fortified resin is initiallydissolved in an organic solvent that is not water-miscible. Thereafter,the aqueous solution of a cationic dispersant and an anionic surfactantare dispersed in the solution. By homogenization in a homogenizer underpressures of 50 to 400 bar, the unstable emulsion becomes a stableemulsion. Finally, the organic solvent is removed by vacuumdistillation.

Paper sizing agents based on rosin dispersions are also disclosed inEuropean Patent Publication 200,002. In addition to rosin, which may bemodified with maleic acid anhydride, fumaric acid, or a modifiedhydrocarbon resin, these sizing agents contain commercially availableprotective colloids or surfactants, polyaluminum hydroxychlorides andpossibly retention, fixing agents, and/or wet-strength imparting agents.Because of their poor electrolyte stability, these dispersions tend toundergo phase separation and to thicken.

Laid-open application DE 3,737,615 discloses a resin emulsion sizingagent which is composed of a fortified resin and an at least partiallyquaternary copolymer composed primarily of a monomer of a (meth)acrylicacid alkyl amino alkyl ester or amide and water. An alleged advantage ofthis sizing agent is that, at a higher pH, in harder water and at ahigher temperature (that is, under conditions in which the conventionalanionic sizing agents no longer perform efficiently) it has a goodsizing effect. This sizing agent is, however, incompatible with acidaluminum salts.

It is therefore an object of the present invention to provide stablesizing agent dispersions for sizing in the neutral and weakly alkalirange which are suitable for internal sizing or only the surface, areadditionally well compatible with aluminum sulfate and can bemanufactured economically without the need for an expensive stirringassembly or other apparatus.

SUMMARY OF THE INVENTION

It was possible to solve this problem in a surprising manner with newsizing agent dispersions containing a novel cationic dispersant,preferably in the form of an aqueous colloidal polymer salt producedfrom monomers (a) through (f):

(a) 10 to 30 weight % N,N-dimethylaminoethyl acrylate and/ormethacrylate;

(b) 5 to 30 weight % of an acrylic and/or methacrylic acid ester of aC₁₁ to C₂₂ fatty alcohol;

(c) 10 to 60 weight % methyl acrylate and/or methacrylate;

(d) 0 to 60 weight % butyl acrylate and/or butyl methacrylate;

(e) 0 to 60 weight % isobutyl acrylate and/or isobutyl methacrylate;

(f) 3 to 15 weight % acrylic acid and/or methacrylic acid; with the sumof components (a) through (f) always being 100 %.

The novel cationic dispersant, which disperses the rosin and/or itsderivatives or the alkyl ketene dimer, is a copolymer which is able toalso function solely as a sizing agent, if required.

The cationic dispersant may also be present as a polymer salt in theform of an aqueous colloidal solution. This form is preferred for themanufacture of the novel sizing agent dispersions.

The nitrogen content of the copolymer is 100 to 250 mMole per 100 g ofthe sum of the weights of monomers (a) through (f). The salt of thecopolymer may be the salt of either an inorganic or an organic acid.Formic acid and acetic acid are particularly suitable for the saltformation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The novel cationic dispersant can be obtained by a radically initiatedpolymerization in solvent of monomers (a) through (f). The solvent is anorganic solvent that is miscible with water, in which monomers (a)through (f) as well as the resulting copolymer dissolve. Preferably,isopropanol is employed. The solvent polymerization is performed in areactor into which monomers (a) through (f) are fed at room temperature.The monomer mixture of the examples is stirred at 120 to I60 rpm.Stirring continues for about 10 minutes in an inert gas atmosphere.Thereafter, the radical initiator dispersed in isopropanol is added. Thereaction temperature is set to reach about 80° C. within 20 minutes andthen the influx of inert gas is interrupted. After about 70 minutes, thepolymerization is completed. Neutralization with acid is advantageouslyperformed immediately after the end of polymerization. The resultingsalt of the copolymer can be converted to a colloidal solution by theaddition of demineralized water.

The novel cationic sizing agent dispersion is composed of the dispersantand a sizing agent and possibly aluminum sulfate. The sizing agentaccording to the present invention is understood to include a reactivesizing agent of the alkyl ketene dimer type as well as a rosin resin ora derivative thereof. The known rosin resins employed are primarilynatural rosins, such as wood rosin, gum rosin and tall oil rosin and therosin derivatives employed are natural rosins modified with maleic acidanhydride and/or fumaric acid, also known as fortified resins. Theserosin derivatives may also be mixed with non-fortified resins. Or, rosinderivatives resulting from the esterification of rosin withpolyalcohols, such as glycerin and pentaerythritol can be employed.

In a particular manner, the novel sizing agent dispersion may also becombined with aluminum salts. Surprisingly this does not result inflocculation or precipitation if aluminum salts are added to thefinished dispersion. According to the present invention, solid ordissolved aluminum salts are added to the finished dispersion whilestirring slowly. The quantity of aluminum salts added to the sizingagent dispersion in solid or dissolved form ranges from 0 to 15 weight%, preferably from 5 to 10 weight %, relative to the finisheddispersion.

Suitable aluminum salts according to the invention are, for example,aluminum sulfate, aluminum formate, aluminum chloride and polyaluminumchloride and other basic aluminum salts.

The sizing agent dispersions according to the present invention canadvantageously also be produced by the inversion method in such a mannerthat the polymer dispersant is reacted directly with the respectivesizing agent in the same reactor in which it was produced. A solution ora melt of, for example, the rosin is added, according to the presentinvention, to the alcoholic solution of the dispersant under intensivestirring at elevated temperature, particularly at 75° to 85° C. Ahomogeneous mixture is formed which is converted into an oil-in-wateremulsion by the gradual addition of warm water having a temperature from75° to 85° C. If required, aluminum salts dissolved in water or solidaluminum salts may be added to this emulsion. The weight ratio ofdispersant to sizing agent is 1:1 to 1:20, particularly 1:7 to 1:12.

This sizing agent dispersion, containing, for example, aluminum sulfate,can be used immediately for sizing paper. A separate addition ofaluminum sulfate is no longer necessary.

The dispersing effect of the novel cationic dispersant on rosin andalkyl ketene dimer, and its compatibility with aluminum salts could notbe derived from the prior art and was therefore even more surprising.

During the so-called phase reversal emulsification, a spontaneousdecrease in viscosity occurs. After cooling of the oil-in-wateremulsion, a white, thin-flowing dispersion is available. Its averageparticle size is less than 0.5 microns.

Another procedure for producing the cationic sizing agent is that thedispersant is added to the sizing agent, present as a melt or asolution, in the form of a colloidal, aqueous solution and is convertedby the subsequent addition of demineralized water and stirring into anoil-in-water emulsion and is thereby dispersed. Solid or dissolvedaluminum salts are then added to the resulting sizing agent dispersion.Thus, a stable sizing agent dispersion results from which the organicsolvent can be removed by distillation under reduced pressure.

In this process variation, the ratio of dispersant to sizing agent isfrom about 1:1 to about 1:20, and particularly from about 1:7 to about1:12.

The examples below serve to demonstrate the production of the novelcationic dispersant and then the production of the sizing agentdispersions according to the present invention and their use for sizingpaper. The examples are given for illustrative purposes only and theyare not intended to limit the scope of the invention.

EXAMPLE 1

An externally heatable double-wall flask having a 500 ml volume is usedas the reaction vessel. It is equipped with a stirrer, reflex condenser,thermometer, gas inlet, bubble counter and drip funnel with gasequalization. At room temperature, the following are successively addedto the flask:

20.0 g isopropanol

32.0 g methyl methacrylate (0.32 Mole)

16.5 g methacrylic acid ester of a C₁₆ -C₁₈ fatty alcohol (0.05 Mole)

15.7 g N,N-dimethylaminoethyl methacrylate (0.01 Mole)

2.5 g acrylic acid (0.035 Mole)

The homogeneous mixture is stirred at a stirrer rate of 150 rpm and isrinsed for 10 minutes in an inert gas, e.g. nitrogen.

Then 0.25 g azobisisobutyronitrile, dispersed in 5 g isopropanol, areadded. The temperature is raised to 80° C. over 20 minutes and once thistemperature has been reached, the supply of nitrogen is cut off.Copolymerization of the monomers begins and reaches the desired degreeof polymerization after about 70 minutes (K-value of 12 indimethylformamide at 25° C. and 1.0 g per 100 ml).

The substance is neutralized with 10 g of a 98% formic acid solution.The polymer salt can be dispersed within 10 minutes by the addition of315 g hot, demineralized water. The temperature of the water is around80° C.

If the dispersion was made in water, an almost colorless, weaklyopalescent colloidal solution results which has a solids content of 16.0weight %. The viscosity of the solution, measured according to aBrookfield viscometer with an H-1 spindle rotating at 50 rpm is 15mPa.s. The content of neutralized nitrogen is 150 mMole per 100 gcopolymer.

EXAMPLE 2

The procedure is the same as in Example 1, but instead of formic acid,10.25 g of a 32% hydrochloric acid solution (0.09 Mole) are employed forthe neutralization. The resulting solution is light, weakly opalescentand has a viscosity of 20 mPa.s. The pH of this polymer solution is 4.0.

Examples 3 to 5 which are listed in Table 1 below relate to furthercopolymer compositions which were produced according to the methoddescribed in Example 1.

                  TABLE 1                                                         ______________________________________                                                      Example                                                         Component*      3         4        5                                          ______________________________________                                        isopropanol     25        20       20                                         methyl methacrylate                                                                           25.1      28       32                                         C.sub.12 -C.sub.14 methacrylate                                                               57.6      --       --                                         C.sub.16 -C.sub.18 methacrylate                                                               --        18.5     16.5                                       N,N-dimethyl amino                                                                            21.5      18       15.7                                       ethyl methacrylate                                                            acrylic acid    10.8      --       2.5                                        methacrylic acid                                                                              --        7.0      --                                         azobisisobutyronitrile                                                                        0.30      0.25     0.25                                       formic acid     17.0      --       4.6                                        hydrochloric acid, 32%                                                                        --        11.8     --                                         water, demineralized                                                                          585       294      325                                        solids (weight %)                                                                             16        18       16                                         mMole/100 g copolymer                                                                         135       160      150                                        appearance      slightly  bright & slightly                                                   turbid    clear    turbid                                     viscosity (mPa · s)                                                                  45        10       20                                         ______________________________________                                         *Unless otherwise indicated, all values are given in grams.              

Examples 6 and 7 show the advantages which are realized if the copolymerof the invention is employed as the sole sizing agent.

Regarding the measured values employed, the following explanations:

(1) The degree of sizing is determined relative to ink with a sizingtester of type PLG-e made by Schroder, Weinheim, as specified in itsoperating instructions. What is measured is the time, in seconds, thatexpired after contact with the testing ink until remission drops to 80%and 50%, respectively, of the remission value of the paper being tested.

Testing ink: paper testing ink, blue, according to DIN (GermanIndustrial Standard) 53126.

(2) The Cobb value according to DIN 53132 indicates the water absorptionof the paper or cardboard in grams per square meter after contact withdistilled water for a certain period of time (1 minute, 5 minutes or 30minutes). The better the sizing effect, the lower the Cobb value.

EXAMPLE 6

An unsized raw paper, produced from 100 weight % bleached coniferouswood sulfate cellulose having a grams per square meter (gsm) substancevalue of 50 is impregnated in a laboratory sizing press made byEinlehner with a sizing liquid which is composed of 5 % enzymaticallydecomposed wheat starch and 8 g sizing agent per liter of this starchsolution, with the sizing agent being produced according to Example 1 or3. The paper is then dried for 2 minutes at 100° C. in a photodryer type64/60 J made by Gerster, Bruchsal. In the sizing press, the paper takesup 4.5 weight % of dry substance.

Under the same conditions, surface sizing is performed with a sizingliquid composed of a commercially available sizing agent based on acopolymer of styrene, butyl acrylate and vinylimidazole having a solidscontent of 20.5 weight %.

The properties measured in the paper are compiled in Table 2.

                  TABLE 2                                                         ______________________________________                                                           Polymer solution                                                    Commercially                                                                            according to the                                                    available invention**                                                         product*  Example 1  Example 3                                       ______________________________________                                        Degree of sizing                                                                         154         804        1150                                        Water 1 minute                                                                            29          25         21                                         (Cobb value)                                                                  ______________________________________                                         *20.5 wt % solids                                                             **16 wt % solids                                                         

This compilation shows the improved sizing effect of the productsaccording to the present invention. Also, the improved sizing effectoccurs with smaller percentages of active substances.

EXAMPLE 7

A filter paperboard made by Macherey & Nagel of Duren according to DIN53106 and having a gsm substance value of 270 is impregnated with asizing liquid composed of 5 % enzymatically decomposed wheat starch and0.06, 0.08 or 0.1 weight % atro, respectively, of polymer solutionproduced according to Example 1 to 5 "% atro" pertains to the absolutecontent of active ingredients in the aqueous dispersion of the sizingagent and indicates the amount of dispersion absolutely present in agiven amount of dry pulp. The temperature of the sizing liquid is 60° C.The commercially available sizing agent based on a copolymer of styrene,butylacrylate and vinylimidazole listed in Table 2, is used forcomparison. The impregnation is effected as follows: The paperboard cutto DIN A4 size is saturated with the sizing liquid for 10 seconds in atray having a capacity of 1.5 liter, is then pressed between otherfilter paperboard by means of a hard rubber roller and then dried for 4minutes at 100° C. in a photodryer made by Gerster/Bruchsal. Theincrease in weight of the cardboard was 5.7 % (starch+polymer). Thefollowing values, listed in Table 3, were measured at the thus sizedcardboard:

                                      TABLE 3                                     __________________________________________________________________________           Commercially                                                                            Polymer solution according to                                       available the invention                                                       product   Example 1 Example 5                                          __________________________________________________________________________    quantity %                                                                           0.06                                                                              0.08                                                                             0.1                                                                              0.06                                                                              0.08                                                                             0.1                                                                              0.06                                                                              0.08                                                                             0.1                                         atro**                                                                        Cobb value*                                                                          320 94 92 108 95 87 100 90 83                                          __________________________________________________________________________     *active period of water: 30 minutes                                           **% size based on the dry weight of the pulp                             

EXAMPLE 8

The copolymerization is performed as in Example 1. The followingingredients are added in succession:

125.6 g isopropanol

50.8 g N,N-dimethylaminoethyl acrylate

67.0 g methyl methacrylate

46.0 g methacrylester of a C₁₆ -C₁₈ fatty alcohol

5.8 g acrylic acid

0.6 g azobisisobutyronitrile

The temperature during the polymerization is round 82° C. and thereaction time is 90 minutes. The viscosity of the solution at the end ofthe polymerization is 6000 mPa.s.

Neutralization is effected with 26.2 g of a 98% formic acid solution.Then 678 g demineralized water having a temperature of 80° C. is addedto the resulting copolymer salt during a period of 15 minutes. Ahomogeneous colloidal solution results which has a solids content of16.8 weight %. The viscosity of the solution, measured with a Brookfieldviscometer with an H-1 spindle rotating at 50 rpm, is 260 mPa.s and thedensity of the solution is 1.02 g/cm³.

The following examples describe the production of dispersions accordingto the invention and their advantageous uses.

EXAMPLE 9

The container described in Example 1 is employed as reactor. The vesselis supplied with 250 g molten wood rosin and this is heated to 100° C.Stirring for a maximum period of 10 minutes, 170 g of the colloidaldispersant produced in Example 8 are added in measured quantities to theheated wood rosin. The result is a slightly yellow water-in-oilemulsion. Then, within 15 minutes, 380 g demineralized water are addedto the water-in-oil emulsion with a stir rate of 600 to 800 rpm. Duringthe addition of the water, a phase reversal occurred and an oil-in-wateremulsion was formed. Finally, 200 g of an aluminum sulfate solutionhaving an equivalent Al₂ O₃ content of 8 weight % was added to theemulsion.

The end product is a stable, dispersion of fine particulates which isparticularly suitable for the overall sizing the entire paper substanceas will be demonstrated below.

The properties of the sizing agent dispersion according to the presentinvention were the following:

    ______________________________________                                        solids content:     35.0 weight %                                             viscosity:          15 mPa · s                                       pH:                 3.0                                                       particle size:      320 nm                                                    ______________________________________                                    

EXAMPLE 10

An indirectly heatable double-wall flask having a 1000 ml volume is usedas the reaction and dispersion vessel. It is equipped with a stirrer,reflux condenser, thermometer, gas inlet and drip funnel. The followingare successively filled into this vessel at room temperature:

35.0 g isopropanol

15.7 g N,N-dimethylaminoethyl acrylate

32.0 g methyl methacrylate

16.6 g methacrylic acid ester of a C₁₆ to C₁₈ fatty alcohol

2.5 g acrylic acid

The mixture is stirred at about 150 rpm and is rinsed with nitrogen.Next, 0.25 g azobisisobutyronitrile are added. The mixture is heated to80° C. in 20 minutes. Then the supply of nitrogen is shut off. Thecopolymerization of the monomers begins spontaneously and reaches thedesired degree of polymerization after about 70 minutes. The resultingsolution is neutralized with 6.9 g formic acid.

Next, 250 g wood rosin heated to 90° C., in the molten state, and 20 gisopropanol are stirred into the polymer salt solution. The polymer saltsolution and the natural resin form a homogeneous mixture. 675 g ofdemineralized water that has a temperature range of 80° to 85° C. isslowly and continuously added. The addition of water is completed after20 minutes. The end product is an oil-in-water emulsion. During theaddition of water, an increase in viscosity is initially noted. Afterthe addition of about two thirds of the intended quantity of water, theprimarily produced water-in-oil emulsion is converted to an oil-in-wateremulsion. A spontaneous drop in viscosity is noted at the point ofreversal. It is advisable for the rate of stirring to be adapted to thechange in viscosity. At the end of the addition of water, the emulsionis cooled to room temperature over a period of 20 minutes.

The resulting product is a white, thin-flowing rosin dispersion whichhas an average particle size of 300 nm and a total solids content of30.2 weight %, with a pH of 5.0 and a viscosity of 28 mPa.s.

According to a special process variation, part of the remaining quantityof water at the end of the phase reversal may also be exchanged forsolutions of salts, polyelectrolytes and other substances. Type andquantity of the exchange liquid are always adapted to the desiredeffect. For example, in rosin dispersions, the remaining quantity ofwater may be exchange for an aluminum sulfate solution or, in ketenedimer dispersions, for a cationic polyelectrolyte solution.

Table 4 below lists Examples 10 to 17, which describe the subject matterof the present invention in even greater detail.

                                      TABLE 4                                     __________________________________________________________________________    Component    Example                                                          (grams)      10   11  12  13  14  15  16  17                                  __________________________________________________________________________    isopropanol  70   55  13.5                                                                              27  30  55  27  45                                  N,N'-dimethylaminoethyl                                                                    16   20.4                                                                              8.1 9.1 16.3                                                                              15.7                                                                              10.2                                                                              15.7                                acrylate                                                                      acrylic acid 2.5  2.5 0.9 1.2 2.1 2.5 1.3 2.5                                 C.sub.16 -C.sub.18 methacrylate                                                            16.5 16.5                                                                              7.3 8   13.2                                                                              16.5                                                                              8.3 16.5                                methylmethacrylate                                                                         32   32  10.7                                                                              15.4                                                                              25.6                                                                              32  16  32                                  azobisisobutyronitrile                                                                     0.25 0.25                                                                              0.10                                                                              0.12                                                                              0.20                                                                              0.25                                                                              0.12                                                                              0.25                                hydrochloric acid 98%                                                                      11.4             8.9 11.4    8.6                                 formic acid 98%   9   3.5 4           4.5                                     demineralized water                                                                        1030 600 618 591 640 314 545 1033                                wood rosin   300  250 250 250         250                                     rosin ester*                  160                                             stearyl ketene dimer              120     200                                 aluminum sulfate solution                                                                       300                 300                                     (including 8% Al.sub.2 O.sub.3)                                               solids content in weight %                                                                 25   32.5                                                                              30.8                                                                              31.8                                                                              24.2                                                                              33  31.5                                                                              20                                  pH           3    3   3.4 3.4 2.8 2.9 2.8 3.2                                 particle size in nm                                                                        220  170 340 370 190 320 320 440                                 viscosity in mPA · s                                                              5    10  10  8   5   25  12  18                                  __________________________________________________________________________     *glycerin ester of a wood rosin having an acid number of 8               

EXAMPLE 18

A cardboard was fabricated of 100 % recycled paper (50% newsprint and50% department store waste) on a Kammerer experimental paper machine toa gsm substance value of 200. The stock consistency was 1.2 weight %.The dilution of the dispersion before applying it to the stock goes upto 0.48%. The dilution was done with backwater. In the machine tub, 0.35% (with reference to the dry substance of the recycled paper) of acationic starch (Hi-cat 100® made by Roquette) were added to thesuspension. The sizing agents were continuously added to the substancestream in measured quantities. The pH of the system was measured at theheadbox. The temperature of the substance at the headbox was about 35°C. Test samples taken from the dried paper panel had a residual moisturecontent of 4 to 5% and were examined, after 24 hours of exposure to 23°C. and 55% relative humidity, as to their degree of sizing. Type andquantity of the added auxiliary substances and the resulting sizingvalues are compiled in Table 5.

                                      TABLE 5                                     __________________________________________________________________________                                                 Commercial product**             Sizing Agent                                                                           Example 10  Example 8   Comparison Example 1*                                                                     as in Example                    __________________________________________________________________________                                                 18                               starting weight                                                                        0.5                                                                              0.5                                                                              0.75                                                                             0.75                                                                             0.5                                                                              0.5                                                                              0.75                                                                             0.75                                                                             0.5                                                                              0.5                                                                              0.75                                                                             0.75                                                                             0.5                                                                              0.5                                                                              0.75                                                                             0.75                    % atro.sup.+                                                                  retention agent***                                                                     0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.02                                                                             0.5                                                                              0.5                                                                              0.75                                                                             0.75                    aluminum sulfate                                                                       -- 0.03                                                                             -- 0.3                                                                              -- 0.3                                                                              -- 0.3                                                                              -- 0.3                                                                              -- 0.3                                                                              -- 0.3                                                                              -- 0.3                     (weight %)****                                                                pH (point of                                                                           7.6                                                                              7.4                                                                              7.6                                                                              7.3                                                                              7.4                                                                              7.2                                                                              7.2                                                                              7.0                                                                              7.6                                                                              7.4                                                                              7.6                                                                              7.4                                                                              7.6                                                                              7.4                                                                              7.5                                                                              7.3                     contact)                                                                      Cobb value water                                                                       170                                                                              125                                                                              120                                                                              95 92 83 58 46 260                                                                              190                                                                              210                                                                              145                                                                              260                                                                              250                                                                              260                                                                              220                     60 sec                                                                        __________________________________________________________________________     *according to Example 18 of DEOS 3,737,615                                    **commercially available rosin dispersion including casein as a protectiv     colloid                                                                       ***cationic polyacrylamide, type 4632 SC made by Nalco                        ****commercially available product containing 17-18% Al.sub.2 O.sub.3         .sup.+ % size based on the dry weight of the pulp                        

EXAMPLE 19

In the same manner as described for Example 18, a paper is producedwhich has the following composition:

40 weight % pine sulfate cellulose

40 weight % beech sulfite cellulose

20 weight % calcium carbonate of type DX 1, made by Omya GmbH

Manufacturing conditions were:

concentration of solids in machine tub: 1.2%

concentration of solids upon contact with substance: 0.28%

gsm basis weight value: 80

stock temperature: 35° C.

Type and quantity of the added auxiliary agents and the resulting sizingvalues are listed in Table 6.

                                      TABLE 6                                     __________________________________________________________________________                                     Example 18 of                                                                             Commercially available           Sizing agent                                                                           Example 10  Example 13  DE-OS 3,737,615                                                                           product as in Example            __________________________________________________________________________                                                 18                               starting weight                                                                        0.6                                                                              0.6                                                                              0.75                                                                             0.75                                                                             0.6                                                                              0.6                                                                              0.75                                                                             0.75                                                                             0.6                                                                              0.6                                                                              0.75                                                                             0.75                                                                             0.6                                                                              0.6                                                                              0.75                                                                             0.75                    % atro*                                                                       starch % 0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                     retention agent %                                                                      0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                                                                            0.015                   cationic                                                                      polyarylamide                                                                 aluminum sulfate                                                                       -- 0.4                                                                              -- 0.4                                                                              -- 0.4                                                                              -- 0.4                                                                              -- 0.4                                                                              -- 0.4                                                                              -- 0.4                                                                              -- 0.4                     (weight %)                                                                    17-18% Al.sub.2 O.sub.3                                                       pH       7.3                                                                              7.1                                                                              7.2                                                                              7.0                                                                              7.3                                                                              7.1                                                                              7.2                                                                              7.0                                                                              7.5                                                                              7.3                                                                              7.5                                                                              7.3                                                                              7.5                                                                              7.3                                                                              7.5                                                                              7.3                     Cobb value water                                                                        36                                                                               31                                                                               28                                                                               23                                                                               38                                                                               32                                                                               27                                                                               23                                                                              115                                                                               95                                                                              115                                                                               86                                                                              120                                                                              115                                                                              120                                                                              100                     60 sec.                                                                       sizing degree, ink                                                                     210                                                                              405                                                                              450                                                                              600                                                                              200                                                                              320                                                                              470                                                                              580                                                                               1  10                                                                               2   25                                                                              0  1  0  6                      seconds                                                                       __________________________________________________________________________     *based on the dry weight of the pulp                                     

EXAMPLE 20

A paper was produced under otherwise the same conditions as in Example19, except ketene dimer dispersions according to the invention wereemployed as sizing agents. Type and quantity of the added auxiliaryagents as well as the resulting sizing values are compiled in Table 7.

TABLE 7

The other listed auxiliary agents correspond to those of Table 6.

                  TABLE 17                                                        ______________________________________                                        The other listed auxiliary agents correspond                                  to those of Table 6.                                                                                           Commercial                                   Sizing agent                                                                           Example 15  Example 17  Product*                                     ______________________________________                                        starting 0.15    0.20    0.15  0.20  0.15  0.20                               weight %                                                                      atro***                                                                       starch % 0.35    0.35    0.35  0.35  0.35  0.35                               retention                                                                              0.02    0.02    0.02  0.02  0.02  0.02                               agent %                                                                       filler content                                                                         17.4    17.0    17.3  16.9  17.3  17.0                               in paper %                                                                    Cobb value                                                                             29      24      31    25    47    38                                 A**                                                                           Cobb value                                                                             21      19      22    19    23    19                                 B**                                                                           degree of                                                                              720     980     640   940   200   280                                sizing A -                                                                    80%                                                                           remission                                                                     degree of                                                                              2400    3300    1800  2950  2050  3000                               sizing B -                                                                    80%                                                                           remission                                                                     ______________________________________                                         *Commercially available merchandise including 6% ketene dimer, total          solids including emulsifying agents (starch, tenside) 7.2 weight %.           **Test result A was directly after manufacture of the paper. Test result      was determined after 96 hours of acclimatization at 23° C. and 55%     relative humidity.                                                            ***based on the dry weight of the pulp.                                  

From the results listed in the above table it is clearly evident thatthe sizing agent according to the present invention produce asignificantly improved instant sizing. Thus, the manufactured paper isavailable for further processing after a shorter storage time, resultingin a significant economic advantage.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be included within the meaningand range of equivalents of the appended claims.

What is claimed is:
 1. A cationic sizing agent dispersion comprising anoil-in-water emulsion of a cationic dispersant produced by(a) providinga colloidal solution of a slat of a copolymer comprising:(i) 10 to 30weight % of a member of the group consisting of N,N-dimethylaminoethylacrylate and N,N-dimethylaminoethyl methacrylate; (ii) 5 to 30 weight %of a member of the group consisting of acrylic acid ester andmethacrylic acid ester of a C₁₀ to C₂₂ fatty alcohol; (iii) 10 to 60weight % of a member of the group consisting of methyl acrylate andmethyl methacrylate; (iv) 0 to 60 weight % of a member of the groupconsisting of n-butyl acrylate and n-butyl acrylate and n-butylmethacrylate; (v) 0 to 60 weight % of a member of the group consistingof isobutyl acrylate and isobutyl methacrylate; (vi) 3 to 15 weight % ofa member of the group consisting of acrylic acid and methacrylic acid;with the sum of the monomers being 100%; polymerized in an organicsolvent which is miscible with water using a radical initiator to form acopolymer, and said copolymer being neutralized with an acid, and theresulting salt of the copolymer being dissolved in demineralized water,to form a colloidal solution of a dispersant; and (b) mixing an alkylketene dimer sizing agent with the colloidal solution to obtain awater-in-oil emulsion, and (c) adding sufficient demineralized water andstirring to convert said water-in-oil emulsion according to an inversionprocess into an oil-in-water emulsion to provide a cationic sizing agentdispersion comprising said oil-in-water emulsion, and an alkyl ketenedimer sizing agent.
 2. A cationic sizing agent dispersion comprising anoil-in-water emulsion of a cationic dispersant produced by(a) providinga colloidal solution of a salt of a copolymer comprising:(i) 10 to 30weight % of a member of the group consisting of N,N-dimethylaminoethylacrylate and N,N-dimethylaminoethyl methacrylate; (ii) 5 to 30 weight %of a member of the group consisting of acrylic acid ester andmethacrylic acid ester of a C₁₀ to C₂₂ fatty alcohol; (iii) 10 to 60weight % of a member of the group consisting of methyl of methylacrylate and methyl methacrylate; (iv) 0 to 60 weight % of a member ofthe group consisting of n-butyl acrylate and n-butyl acrylate andn-butyl methacrylate; (v) 0 to 60 weight % of a member of the groupconsisting of isobutyl acrylate and isobutyl methacrylate; (vi) 3 to 15weight % of a member of the group consisting of acrylic acid andmethacrylic acid; with the sum of the monomers being 100%; polymerizedin an organic solvent which is miscible with water using a radicalinitiator to form a copolymer, and said copolymer being neutralized withan acid, and the resulting salt of the copolymer being dissolved indemineralized water, to form a colloidal solution of a dispersant; and(b) mixing a rosin resin sizing agent selected from the group consistingof natural resins, fortified resins, esters of natural resins andmixtures thereof with the colloidal solution to obtain a water-in-oilemulsion, and (c) adding sufficient demineralized water and stirring toconvert said water-in-oil emulsion according to an inversion processinto an oil-in-water emulsion to provide a cationic sizing agentdispersion comprising said oil-in-water emulsion, and a rosin resinsizing agent selected from the group consisting of natural resins,fortified resins, esters of natural resins and mixtures thereof.
 3. Acationic sizing agent dispersion comprising an oil-in-water emulsion ofa cationic dispersant produced by(a) providing a colloidal solution of asalt of a copolymer comprising:(i) 10 to 30 weight % of a member of thegroup consisting of N,N-dimethylaminoethyl acrylate andN,N-dimethylaminoethyl methacrylate; (ii) 5 to 30 weight % of a memberof the group consisting of acrylic acid ester and methacrylic acid esterof a C₁₀ to C₂₂ fatty alcohol; (iii) 10 to 60 weight % of a member ofthe group consisting of methyl acrylate and methyl methacrylate; (iv) 0to 60 weight % of a member of the group consisting of n-butyl acrylateand n-butyl acrylate and n-butyl methacrylate; (v) 0 to 60 weight % of amember of the group consisting of isobutyl acrylate and isobutylmethacrylate; (vi) 3 to 15 weight % of a member of the group consistingof acrylic acid and methacrylic acid; with the sum of the monomers being100%; polymerized in an organic solvent which is miscible with waterusing a radical initiator to form a copolymer, and said copolymer beingneutralized with an acid, and the resulting salt of the copolymer beingdissolved in demineralized water, to form a colloidal solution of adispersant; and (b) mixing a sizing agent with the colloidal solution toobtain a water-in-oil emulsion, and (c) adding sufficient demineralizedwater and stirring to convert said water-in-oil emulsion according to aninversion process into an oil-in-water emulsion to provide a cationicsizing agent dispersion comprising said oil-in-water emulsion, and 0 to15 weight % aluminum salts, with reference to the finished dispersion.4. A cationic sizing agent dispersion as set forth in claim 3 including5 to 10 weight % aluminum salts, with reference to the finisheddispersion.
 5. A method of producing a cationic sizing agent dispersioncomprising the steps of:(a) preparing a dispersant comprising acolloidal solution f a salt of a copolymer comprising(i) 10 to 30 weight% of a member of the group consisting of N,N-dimethylaminoethyl acrylateand N,N-dimethylaminoethyl methacrylate; (ii) 5 to 30 weight % of amember of the group consisting of acrylic acid ester and methacrylicacid ester of a C₁₀ to C₂₂ fatty alcohol; (iii) 10 to 60 weight % of amember of the group consisting of methyl acrylate and methylmethacrylate; (iv) 0 to 60 weight % of a member of the group consistingof n-butyl acrylate and n-butyl acrylate and n-butyl methacrylate; (v) 0to 60 weight % of a member of the group consisting of isobutyl acrylateand isobutyl methacrylate; (vi) 3 to 15 weight % of a member of thegroup consisting of acrylic acid and methacrylic acid; with the sum ofthe monomers being 100%; polymerizing said monomers in an organicsolvent which is miscible with water using a radical initiator to form acopolymer, neutralizing said copolymer with an acid to form a salt ofthe copolymer, and mixing said copolymer salt in demineralized water, toform a colloidal solution of a dispersant; (b) mixing a sizing agentwith the colloidal solution to form a water-in-oil emulsion, and (c)adding sufficient demineralized water and stirring, to convert saidwater-in-oil emulsion according to an inversion process, into anoil-in-water emulsion and provide a cationic sizing agent dispersion. 6.A method of producing a cationic sizing agent dispersion as defined inclaim 5, wherein the sizing agent is presented in the form of a melt. 7.A method of producing a cationic sizing agent dispersion as defined inclaim 5, wherein the sizing agent is presented in the form of a solutionin an organic solvent.
 8. A method of producing a cationic sizing agentdispersion as defined in claim 5, further comprising the step of addingdissolved or solid aluminum salt.
 9. A method of producing a cationicsizing agent dispersion as defined in claim 5, wherein the weight ratioof the dispersant to the sizing agent is between 1:1 and 1:20.
 10. Amethod of producing a cationic sizing agent dispersion as defined inclaim 5, wherein the weight ratio of the dispersant to the sizing agentis between 1:7 and 1:12.
 11. A method of producing a cationic sizingagent dispersion as defined in claim 5, further comprising removing theorganic solvent from the dispersant by distillation.